Foam Compositions and Articles Including Cyclodextrin Crosslinked with Polyurethane Prepolymer and Preparation Thereof

ABSTRACT

An odor-absorbing foam composition comprising a cyclodextrin crosslinked with a polyurethane prepolymer. In one embodiment, the foam includes a ratio of the cyclodextrin to the polyurethane prepolymer selected to result in formation of the foam. The odor-absorbing foam may be used in a personal care product or wound care. A process for preparing a foam, including providing a cyclodextrin; providing a polyurethane prepolymer; combining the cyclodextrin with the polyurethane prepolymer; and allowing the polyurethane prepolymer to react with water and crosslink the cyclodextrin to form the foam. A process for preparing an odor-absorbing foam article such as a personal care product, including preparing the foam and applying it or the components thereof to a suitable substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. application Ser. No.12/530,851 filed Sep. 13, 2009, which is a 371 of InternationalApplication No. PCT/US2008/056554, which was published in English onSep. 18, 2008, which claims the benefit of U.S. Provisional ApplicationNo. 60/894,494 filed Mar. 13, 2007.

TECHNICAL FIELD

The present invention relates to foam compositions including acyclodextrin crosslinked with a polyurethane prepolymer, and to articlescontaining such foam compositions, and to methods of preparationthereof. The cyclodextrin may be unmodified or modified.

RELATED ART

Cyclodextrins are cyclic molecules including, most commonly, six, sevenor eight alpha-D-(+)-glucopyranose rings bonded together by 1,4linkages. The common cyclodextrins, having six, seven or eight rings arereferred to as alpha-(α-), beta-(β-) and gamma-(γ-)cyclodextrin,respectively. These cyclodextrins may be conveniently referred to inabbreviated form as α-CD, β-CD and γ-CD, respectively, and cyclodextringenerally may be referred to as CD. Larger cyclodextrins have beenisolated, but are not commonly used. Cyclodextrins are non-reducingalpha-1,4-maltooligosaccharides. Cyclodextrins are formed enzymaticallyfrom starch by the action of cyclodextrin glycosyltransferase(EC.3.2.1.19) produced from certain microorganisms.

Cyclodextrins are known to be useful for their ability to reversiblyform inclusion complexes, sometimes referred to as clathrates, with manytypes of compounds. This ability results from the molecular shape, whichhas been likened to a doughnut or a truncated cone with acylindrically-shaped cavity formed in the center of the doughnut ortruncated cone. The outer surface of cyclodextrin is generallyhydrophilic, while the interior cavity is generally hydrophobic. Thehydrophilic outer portion allows free cyclodextrins to be water soluble.The hydrophobic interior cavity allows the cyclodextrins to absorb orform inclusion complexes with, e.g., organic compounds of appropriatesize. In α-CD, the interior cavity has a diameter of about 5 angstroms;the interior cavity of β-CD has a diameter of about 7 angstroms, and theinterior cavity of γ-CD has a diameter of about 9 angstroms. Theinterior cavities of all three cyclodextrins have a depth of about 7angstroms.

A need remains for foams capable of absorbing relatively largequantities of water without losing the foam character. A need remainsfor foams capable of absorbing water and swelling to two or more timesthe original volume of the foam. A need remains for foams capable ofabsorbing water and gaining weight to two or more times the originalvolume of the foam. A need remains for foams capable of absorbing odorsand/or that are capable of holding and delivering agents such aspharmaceuticals, perfumes, and other materials such as antimicrobialagents, skin wellness and health care agents, and are capable ofmaintaining their foam character when wetted. A need remains for foamsexhibiting combinations of these features, as well as for foamsexhibiting these and combinations with additional features, such as, forexample, foams which have an easily controllable crosslinking reactionas it polymerizes, and the formation of gas bubbles within the structureof the foam, while retaining the capability of absorbing relativelylarge quantities of water and absorbing odors, without losing the foamcharacter.

SUMMARY

In one embodiment, the present invention relates to foam compositionincluding a cyclodextrin crosslinked with a polyurethane prepolymer andhaving a foam structure. In one embodiment, the foam is made with aratio of the water to the cyclodextrin and to the polyurethaneprepolymer selected to result in formation of the foam.

In another embodiment, the present invention relates to processincluding providing a cyclodextrin; providing a polyurethane prepolymer;providing water; and combining the cyclodextrin, the water and thepolyurethane prepolymer; and reacting the polyurethane prepolymer withthe water and the cyclodextrin to form a foam composition comprising thecyclodextrin crosslinked with the polyurethane prepolymer and having afoam structure.

In another embodiment, the present invention relates to a process forpreparing a foam-containing personal care product, including providing acyclodextrin; providing a polyurethane prepolymer; providing water; andcombining the cyclodextrin, the water and the polyurethane prepolymer;reacting the polyurethane prepolymer with the water and the cyclodextrinto form a foam composition comprising the cyclodextrin crosslinked withthe polyurethane prepolymer and having a foam structure; and applyingthe cyclodextrin, the water and the polyurethane prepolymer to asubstrate. The substrate may be or include an element of the personalcare product. The element may be or include a backing layer on at leasta portion of which the foam forms a layer. The personal care product maybe one or more of a bandage, a wound dressing, a wipe, a diaper, adiaper pant, a training pant, an absorbent underpant, a protectiveswimming undergarment, an incontinence garment, a panty shield or liner,a feminine hygiene product or a perspiration shield.

In another embodiment, the present invention relates to a personal careproduct including a foam composition applied to a substrate, in whichthe foam composition includes a cyclodextrin crosslinked with apolyurethane prepolymer and having a foam structure, in which a ratio ofwater to the cyclodextrin and the polyurethane prepolymer has beenselected to result in formation of the foam structure when thepolyurethane prepolymer is reacted with the water and the cyclodextrin.

In accordance with the invention, the cyclodextrin may be a modifiedcyclodextrin, an unmodified (natural or native) cyclodextrin or amixture of any two or more thereof. In accordance with the invention,the cyclodextrin may be or may be derived from (in the case of amodified cyclodextrin) an α-cyclodextrin, a β-cyclodextrin, aγ-cyclodextrin or a mixture of any two or more thereof.

In one embodiment, the foam composition further includes non-crosslinkedcyclodextrin. The non-crosslinked cyclodextrin may include free modifiedand/or unmodified cyclodextrin, modified and/or unmodified cyclodextrinsingly bonded to the polyurethane prepolymer or a mixture of any two ormore thereof. “Free” cyclodextrin, modified or unmodified, is notchemically bonded to the polyurethane-cyclodextrin structure.

In one embodiment, a portion of the cyclodextrin and/or modifiedcyclodextrin is complexed. The cyclodextrin may be complexed, e.g., withan antimicrobial agent or other moieties described in more detail below.

In accordance with one embodiment, the cyclodextrin provides improvedodor absorption due to the odor absorbing characteristics of thecyclodextrin. In addition, the cyclodextrin may stiffen and/or provide astabilizing effect to the foam by virtue of its having been crosslinkedinto the foam structure. By controlling the relative amounts ofcyclodextrin, water and polyurethane prepolymer and, in someembodiments, other ingredients such as polyether and/or polyesterpolyols, the exact physical characteristics of the foam, e.g., itsstiffness, rigidity and/or flexibility, can be controlled and adjusted.The quantity of water in the reaction mixture relative to thecyclodextrin and the polyurethane prepolymer is controlled to obtain afoam rather than a hydrogel. In one embodiment, the quantity of waterrelative to the cyclodextrin and the polyurethane prepolymer in thereaction mixture is controlled to avoid formation of a hydrogel.

As used herein, the term “cyclodextrin” refers collectively andgenerally to any of the cyclodextrins disclosed herein, whether modifiedor unmodified, complexed or not complexed, except where specificcyclodextrins are referred to by a more specific identification.

The present invention, in its various embodiments, thus addresses theneeds described above. That is, in one embodiment, the foam is capableof absorbing relatively large quantities of water, i.e., at least about20% of the original foam weight. In another embodiment, the foam iscapable of absorbing water and increasing its weight by 20% to about3000% of its original weight. In another embodiment, the foam is capableof absorbing water and increasing its weight by 100% to about 2000% ofits original weight. In another embodiment, the foam is capable ofabsorbing water and increasing its weight by 200% to about 1600% of itsoriginal weight. In another embodiment, the foam is capable of absorbingodors and/or delivering various agents such as pharmaceuticals,perfumes, antimicrobial agents, skin wellness and health care agents andother materials which may be complexed with the cyclodextrin in the foamor may be otherwise incorporated into the foam. In another embodiment,the foam exhibits various combinations of these features.

In other embodiments, the present invention provides an easilycontrollable crosslinking and foam forming reaction as the cyclodextrin,water and polyurethane prepolymer polymerize, including the formation ofgas bubbles within the structure of the foam. The foam product includesthe capabilities of absorbing relatively large quantities of water andof absorbing odors. In other embodiments, the foam exhibits variouscombinations of the foregoing features and additional features, such asfor example, including delivery of medicaments, including perfumes orother materials carried in the foam or complexed with the cyclodextrin.Thus the foam can be used to deliver the medicaments or absorb odors orprovide a pleasing odor to help mask any odors emanating from the woundbeing treated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a β-cyclodextrin molecule.

DETAILED DESCRIPTION

“Foam” refers to a two-phase gas-solid system that has a supportingsolid lattice of cell walls which are continuous throughout thestructure. The gas (typically air or carbon dioxide) phase in a foam isusually distributed in void pockets called cells. The supporting solidmay be relatively rigid or flexible.

“Open-cell foams” are polymeric materials having substantial void spacein the form of cells defined by a plurality of mutually connected, threedimensionally branched webs of polymeric material, wherein the cellstypically have openings to permit fluid communication from one cell toanother. That is, the individual cells of the foam are generally notcompletely discrete from each other. The cells in open-cell foams haveintercellular openings, or “windows” which are large enough to permitfluid transfer from one cell to another within the foam structure.

In one embodiment, the present invention relates to a foam compositioncomprising a modified cyclodextrin crosslinked with a polyurethaneprepolymer and water. In one embodiment, a ratio of the modifiedcyclodextrin to the water and to the polyurethane prepolymer is selectedto result in formation of the foam. That is, while it is possible tocombine a cyclodextrin with water and a polyurethane prepolymer in awide range of ratios, in the present invention, the ratio is selected,and the reaction conditions are selected, such that a foam, as definedherein, is formed from the crosslinking reaction between the modifiedcyclodextrin, the water and the polyurethane prepolymer.

In accordance with embodiments of the present invention, polyurethanefoams are prepared by reacting organic polyfunctional isocyanates(polyurethane prepolymers) with cyclodextrins and optionally otherorganic polyols. For crosslinking, the cyclodextrins or polyols have twoor more isocyanate-reactive hydrogen atoms. When this reaction isconducted under anhydrous conditions and in the absence of gas formingreagents the resulting polyurethane is substantially non-porous. If acellular or foam product is desired, a blowing agent, which may contain,for example, water and an excess of the of the polyfunctionalisocyanate, is present in the initial reactant mixture. As is known inthe art, the reaction of the water with the isocyanate compound producescarbon dioxide, which is temporally entrapped in the reaction mixture asit solidifies and forms a network of interconnecting open cells. Thedensity of the resultant foam is dependent on the amount of excessisocyanate and water employed. The foam composition can be maderelatively flexible or rigid depending upon the degree of crosslinkingthat takes place within the molecules, during the reaction to producethe foam, as well as on the specific cyclodextrins and/or other polyolsthat are present. The degree of crosslinking within a foam is determinedby the number of active hydroxyl groups (e.g., 2-6 usually, as known,however more are possible in cyclodextrin) within the polyol structure.

Foam compositions are made when a disperse phase is combined with waterto produce gas bubbles as it polymerizes, resulting in a solid materialwith multiple pores of either trapped gas or open cells throughout thestructure. This reaction can proceed to result in a foam that isprimarily a reticulated open-celled structure or a closed cellstructure, or a combination of both. A foam composition is flexible orrigid depending upon the degree of crosslinking that takes place withinthe molecules, during the reaction to produce a foam. The degree ofcrosslinking within a foam is determined by the number of activehydroxyl groups (e.g., 2-6 or more) within the structure. For example,if unmodified cyclodextrin is used and no water is added, a quite rigidpolyurethane with little or no foam character would be expected, whereasusing a cyclodextrin, optionally adding an additional polyol (such as apolyether polyol) and water, should result in the formation of a foamthat may be relatively flexible, particularly where the reaction iscarried out at an elevated temperature and including an polyetherpolyol. It is noted that β-cyclodextrin, for example, having 3 hydroxylgroups on each of 7 glucopyranose rings, has a total of 21 potentiallycross-linkable sites. While it is unlikely in which all 21 had beenreacted could be obtained, it is clearly possible for a cyclodextrin tobe highly crosslinked and, by the same token, it is possible for acyclodextrin to be highly modified.

A foam, as used herein, is a polymeric material which exhibits theability to swell in water or to absorb at least 20% of its weight ofwater to which it is exposed and to retain at least a portion of thewater within its structure without losing its foam character andstructural integrity.

Addition of the “non-cyclodextrin” polyol, e.g., a polyether polyol, tothe polyurethane prepolymer polymerization/crosslinking reaction resultsin the formation of soft rubbery polyurethane segments together with themore rigid polyurethane segments produced by the cyclodextrin reactionwith the polyurethane prepolymer. Such flexible foams that may beparticularly useful in wound treatment, drug delivery and other medicalapplications.

In one embodiment, the foam structure is an open cell foam. In anotherembodiment, the foam structure is a closed cell foam. In anotherembodiment, the foam structure is a microcellular foam. In anotherembodiment, the foam structure is a combination of two or more of thesefoam structures.

Non-Modified and Modified Cyclodextrins

As discussed above, the most common cyclodextrins are alpha-(α-),beta-(β-) and gamma-(γ-)cyclodextrin, having 6, 7 or 8 glucopyranoserings in each cyclodextrin molecule, respectively. Native or natural,i.e., unmodified, cyclodextrin includes three hydroxyl groups on eachglucopyranose ring. Each of the hydroxyl groups is anisocyanate-reactive group. In one embodiment, such unmodified or nativecyclodextrins may be used to prepare the foam composition of the presentinvention.

In another embodiment, since the isocyanate reactivity of thecyclodextrin hydroxyl groups is restricted or reduced to some degree(due to steric effects of the remainder of the cyclodextrin moleculecompared to hydroxyl groups in molecules in which the hydroxyl group ismore easily accessible) it is helpful to prepare modified cyclodextrinsby addition of groups providing better steric access to active hydrogensfor reaction with the reactive isocyanate groups. Thus, to increase thereactivity of the cyclodextrin to the reactive isocyanate groups of thepolyurethane prepolymer, it has been found useful to modify thecyclodextrin by functionalization with groups such as 2-hydroxy propyl,which can be introduced to the cyclodextrin by known reactions or can beobtained commercially.

In one embodiment, the modified cyclodextrin is modified by being bondedto a moiety comprising at least one isocyanate-reactive group. In manyisocyanate-reactive groups, the reactivity results from the presence ofan active hydrogen. Examples of suitable moieties comprisingisocyanate-reactive groups include a hydroxyalkyl group, an aminoalkylgroup, a carboxyl group, a sulfhydryl group, an epoxy group, or acombination of any two or more thereof. Of these, all but the epoxyinclude an active hydrogen, and the epoxy is sufficiently reactive toreact with an isocyanate group. In one embodiment, the term “activehydrogen” refers to a moiety containing a hydrogen atom which, becauseof its position in the molecule, displays significant activity accordingto the Zerewitnoff test, described by Wohler in JACS, Vol. 49, p. 3181(1927). Illustrative active hydrogen moieties include —COOH, —OH, —NH₂,NH—, CONH₂, —CONH— and —SH. The modifying group may be introduced byknown methods, such as by use of an epoxy or other group capable ofreaction with one of the primary or secondary hydroxyl groups on theunmodified cyclodextrin.

As described above, cyclodextrins include six, seven or eight, andpossibly more, glucopyranose rings. Each glucopyranose ring includesthree hydroxyl groups, two secondary hydroxyl groups attached to carbonatoms on the ring itself and one primary hydroxyl group attached to themethylene carbon attached to the ring. A schematic diagram or drawing ofa β-cyclodextrin molecule is shown in FIG. 1, in which the hydroxylgroups are shown as —OR groups. In FIG. 1, the hydroxyl groups on thelower side are the secondary hydroxyls, and the hydroxyl groups on theupper side are the primary hydroxyls. As noted above, there are threehydroxyl groups on each glucopyranose ring, each of which is capable ofreacting with an appropriate group to form either a crosslinking bond ora derivatizing or modifying bond. Each of the three hydroxyl groups oneach of the glucopyranose rings of the cyclodextrin exhibits slightlydifferent reactivity. As suggested by FIG. 1, the hydroxyl groups areaccessible but may be somewhat sterically hindered, thus exhibitinglower reactivity than would hydroxyl groups on, e.g., a singleglucopyranose ring.

In order to enhance the availability of reactive sites, and thus toincrease the isocyanate reactivity of the cyclodextrin as a whole, thecyclodextrin may be modified or derivatized. In this regard, it is notedthat in FIG. 1, rather than —OH groups, —OR groups are shown, suggestingthat R may be other than hydrogen. Thus, in the cyclodextrin shown inFIG. 1, the R groups can be hydrogen or any one of a number ofsubstituents, such as hydroxypropyl, amino, amido, and carboxyl, just toname a few. Cyclodextrin may be modified with a wide variety of groups.In many such embodiments, the derivative is formed through a bond to theoxygen atom of one or more of the three available hydroxyl groups on theglucopyranose rings of the cyclodextrin. In one embodiment, thesubstituent includes the reactive moiety, i.e., the —OH, —SH, —NH₂, orother group, on the terminal carbon atom, that is on the carbon atommost distant from the cyclodextrin molecule. However, the reactivemoiety may be on any carbon atom in the modifying group.

In one embodiment, the modified cyclodextrin of the present invention ismodified by derivitization by a hydroxyalkyl group (—ROH), an aminoalkylgroup (—RNH₂ or —RNHR′), an alkyl-carboxyl group (—RCOOH), analkylsulfhydryl group (—RSH), an epoxy group, or a combination of anytwo or more thereof.

In one embodiment, the modified cyclodextrin includes a C₁-C₆ mono-, di-or higher hydroxyalkyl group, such as a hydroxymethyl, hydroxyethyl, 2-or 3-hydroxy-n-propyl, 2- or 3-hydroxyisopropyl, alcohols of higheralkyl groups (C₇ or higher, up to at least C₁₂), and diols, triols andhigher polyols of such alkyl groups. The hydroxyl group(s) may be on anycarbon atom of the alkyl group. In one embodiment, in the above noted—ROH, R may range from C₁ to about C₆, and in another embodiment, R mayrange from C₁ up to at least C₁₂. In one embodiment, the modifiedcyclodextrin is 2-hydroxypropyl cyclodextrin, and in one embodiment, themodified cyclodextrin is 2-hydroxypropyl β-cyclodextrin, a particularlywell known and well-studied modified cyclodextrin. In anotherembodiment, the modified cyclodextrin is 3-hydroxypropyl cyclodextrin.In the 3-hydroxypropyl cyclodextrin, the hydroxyl group should be moresterically accessible for reaction by, e.g., the reactive isocyanate ofa polyurethane prepolymer.

In one embodiment, the modified cyclodextrin includes an alkyl-thiol oralkyl-sulfhydryl group, that is an alkyl group containing an —SHsubstituent. The hydrogen on the —SH group is an active hydrogen.Suitable alkylthiols are any corresponding to the above-identified mono-or poly-hydroxyalkyl groups. The thiol group(s) may be on any carbonatom of the alkyl group. In one embodiment, in the above noted —RSH, Rmay range from C₁ to about C₆, and in another embodiment, R may rangefrom C₁ up to at least C₁₂.

In one embodiment, the modified cyclodextrin includes an aminoalkylgroup, that is, an alkyl group containing an amine moiety. In oneembodiment, the amine moiety is either a primary or secondary amine,both of which have an active hydrogen. Suitable aminoalkyl groupsinclude, for example, alkyl groups having one or more primary orsecondary amine groups, and from 1 to about 12 carbon atoms, in oneembodiment from 1 to about 8 carbon atoms, and in another embodimentfrom 1 to about 6 carbon atoms, and in still another embodiment, 1, 2 or3 carbon atoms. The amino group(s) may be on any carbon atom of thealkyl group. In one embodiment, in the above noted —RNH₂ or —RNHR′, Rand R′ independently may range from C₁ to about C₆, and in anotherembodiment, R may range from C₁ up to at least C₁₂. In addition, asnoted above, in one embodiment, the modified cyclodextrin may include anamide, either primary or secondary, corresponding to any of theforegoing amines and the following carboxylic acids. In one embodiment,the reaction of an amine with a given polyurethane prepolymer is muchfaster than the reaction of a hydroxyl group with the given polyurethaneprepolymer.

In one embodiment, the modified cyclodextrin includes a carboxyl group,i.e., a —RCOOH group, where R may be a bond to the oxygen atom of thecyclodextrin, or a C₁ to about a C₁₂ alkyl group. Thus, for example, thecyclodextrin may be substituted with a formyl, acetyl, propionyl, orhigher alkyl-carboxyl group. The carboxyl group(s) may be on any carbonatom of the alkyl group. In one embodiment, in the above noted —RCOOH, Rmay range from C₁ to about C₆, and in another embodiment, R may rangefrom C₁ up to at least C₁₂

In one embodiment, the modified cyclodextrin includes an epoxy group,i.e., a group having a general formula:

where R may be a bond to the oxygen atom of the cyclodextrin, or a C₁ toabout a C₁₂ alkyl group. The epoxy group(s) may be on any carbon atom ofthe alkyl group.

In one embodiment, in any of the above substituted cyclodextrins, R maybe a cycloalkyl group, an aryl group, an alkylaryl group, an arylalkylgroup, an ether-containing group, or other known group capable ofattachment to the cyclodextrin molecule via one of the hydroxyl groups,alternative to the alkyl groups described above, and containing at leastone isocyanate-reactive group in the R group. In one embodiment, any ofthese “linking” groups may be used, with the proviso that thecyclodextrin is substituted with a group including a reactive moiety,such as the active hydrogen mentioned above, that functions to increasethe ability of the cyclodextrin molecule to be crosslinked in formingthe foam of the present invention.

Suitable methods are known in the art for forming the foregoing modifiedcyclodextrins. Suitable methods for preparation of a wide variety ofsuitably modified cyclodextrins are disclosed in Croft et al.,“Synthesis of Chemically Modified Cyclodextrins”, Tetrahedron, Vol. 39,No. 9, pp. 1417-1474, 1983, in. In addition, modified cyclodextrins arecommercially available commercially, for example, from CyDex, Inc.,Lenexa, Kans., from CycloLab Ltd., Budapest, Hungary, and fromCyclodextrin Technologies Development, Inc., High Springs, Fla.

In one embodiment, the content of the cyclodextrin in the composition isin the range from about 0.5 wt % to about 50 wt %, and in anotherembodiment, the content of the cyclodextrin in the composition is in therange from about 1 wt % to about 40 wt %, and in another embodiment, thecontent of the cyclodextrin in the composition is in the range fromabout 3 wt % to about 20 wt %, and in another embodiment, the content ofthe cyclodextrin in the composition is in the range from about 5 wt % toabout 10 wt %. The foregoing weight percentages are based on the totalweight of the composition, prior to the crosslinking, foaming and dryingsteps.

Here and throughout the specification and claims, the numerical limitsof the ranges and ratios may be combined. Thus, for example, in theforegoing, although a range of about 1 wt % to about 10 wt % is notspecifically recited, it is deemed to be within the scope of thedisclosure. In addition, all integral values within the foregoing rangesare deemed to be disclosed, even if not specifically mentioned orexemplified.

Polyurethane Prepolymer

In one embodiment, the polyurethane prepolymer comprises a reactiveisocyanate moiety. In one embodiment, the reactive isocyanate moietycomprises an aliphatic, cycloaliphatic, arylaliphatic, heterocyclic oraromatic polyisocyanate or a mixture thereof.

In one embodiment, the polyurethane prepolymer has an average isocyanatefunctionality of about 2 or greater. In another embodiment, thepolyurethane prepolymer has an average isocyanate functionality of about2.2 or greater, and in another embodiment, the polyurethane prepolymerhas an average isocyanate functionality of about 2.5 or greater, and inyet another embodiment, the polyurethane prepolymer has an averageisocyanate functionality of about 3 or greater, while in still anotherembodiment, the polyurethane prepolymer has an average isocyanatefunctionality of about 4 or greater.

Examples of such polyisocyanates include ethylene diisocyanate,1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate,1,12-dodecane diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate andmixtures of these isomers; 2,4- and 2,6-toluene diisocyanate andmixtures of these isomers, 1,3- and/or 1,4-phenylene diisocyanate, 2,5′-and/or 4,4′-diphenyl methane diisocyanate, and mixtures of theseisomers, diphenyl methane-2,4′- and/or 4,4′-diisocyanate,naphthylene-1,5-diisocyanate, triphenyl methane-4,4′,4″-triisocyanate,polyphenyl polymethylene polyisocyanates and similar knownpolyisocyanates. In one embodiment, the polyisocyanate used as thepolyurethane prepolymer is one of the toluene diisocyanates.

In one embodiment, the polyurethane prepolymer comprises apolyisocyanate such as toluene-2,4-diisocyanate,toluene-2,6-diisocyanate, a mixture of toluene 2,4-diisocyanate andtoluene-2,6-diisocyanate, m-phenyl-diisocyanate,3,3′-diphenyl-4,4′-biphenylene diisocyanate; 4,4′-biphenylenediisocyanate; 4,4′-diphenylmethane diisocyanate;3,3′-dichloro-4,4′-biphenylene diisocyanate; cumene-2,4-diisocyanate;1,5-napthalene diisocyanate; p-phenylene diisocyanate;4-methoxy-1,3-phenylene diisocyanate; 4-chloro-1,3-phenylenediisocyanate; 4-bromo-1,3-phenylene diisocyanate; 4-ethoxy-1,3-phenylenediisocyanate; 2,4-dimethyl-1,3-phenylene diisocyanate;5,6-dimethyl-1,3-phenylene diisocyanate; 2,4-diisocyanatodiphenylether;4,4′-diisocyanatodiphenylether benzidine diisocyanate;4,6-dimethyl-1,3-phenylene diisocyanate; 9,10-anthracene diisocyanate;4,4′-diisocyanatodibenzyl;3,3′-dimethyl-4,4′-diisocyanatodiphenylmethane;2,6-dimethyl-4,4′-diisocyanatodiphenyl; 2,4-diisocyanatostilbene;3,3′-dimethoxy-4,4′-diisocyanatodiphenyl; 1,4-anthracene diisocyanate;2,5-fluorene diisocyanate; 1,8-naphthalene diisocyanate;2,6-diisocyanatobenzfuran; 2,4,6-toluene triisocyanate;p,p′,p″-triphenylmethane triisocyanate; polymeric 4,4′-diphenylmethanediisocyanate; isophorone diisocyanate, hexamethylene diisocyanate,trans-1-4 cyclohexyl diisocyanate, 2,4- and 2,6-hexahydrotoluenediisocyanate, 4,4′-, 2,2′-, or 2,4′-dicyclohexylmethane diisocyanate, or1,3,5-tricyanatocyclohexane, or mixtures or combinations of any two ormore of the foregoing. In one embodiment, the polyisocyanate isisophorone diisocyanate.

In one embodiment, the polyurethane prepolymer may be a partiallypolymerized polyurethane polymer having unreacted isocyanate groupssuitable for crosslinking the modified cyclodextrins. Thus, for example,in one embodiment, the polyurethane prepolymer may be a reaction productof a polyether polyol with an excess of polyisocyanate, in which apolyurethane has been formed, but in which reactive isocyanate groupsremain as end groups on the polymer chains. In one embodiment, thepolyether polyol is a lower alkyl polyether polyol, for example, amethyl, ethyl, propyl or butyl polyether polyol, or mixtures andcombinations of two or more thereof. The alkyl groups may be branched orun-branched.

The polyurethane prepolymer may be a capped product of the reaction ofan excess of a suitable diisocyanate with a polyoxyalkylene polyol, inwhich there are substantially no free hydroxyl groups, and most or allof the polymer chains are terminated or capped with reactive isocyanategroups, and each polymer molecule has an isocyanate functionality of atleast two. This capped product, if reacted with water, can be used toform a conventional polyurethane foam. The polyoxyalkylene polyol, inone embodiment, has a molecular weight of about 200 to about 20,000, andin one embodiment, has a molecular weight from about 600 to about 6,000,with a hydroxyl functionality per polymer molecule of at least 2, and inone embodiment, a hydroxyl functionality per polymer molecule from 2 toabout 6. Suitable polyalkylene polyols include, for example,polyethylene oxide and the copolymer of ethylene oxide and propyleneoxide. Additional information relating to formation of such partiallypolymerized polyurethane prepolymers, exemplary reactants and suitablereaction conditions may be found, for example, in U.S. Pat. No.3,861,993, the disclosure of which relating to formation of partiallypolymerized polyurethane prepolymer, the reactants and reactionconditions, is incorporated by reference herein.

In one embodiment, the partially polymerized polyurethane prepolymer hasa weight average molecular weight in the range from about 500 to about30,000 or higher. In one embodiment, the partially polymerizedpolyurethane prepolymer has a weight average molecular weight in therange from about 500 to about 10,000. In one embodiment, the partiallypolymerized polyurethane prepolymer has a weight average molecularweight in the range from about 1000 to about 5,000. In one embodiment,on average, each molecule of the partially polymerized polyurethaneprepolymer has an isocyanate functionality of about two or greater. Inone embodiment, on average, each molecule of the partially polymerizedpolyurethane prepolymer has a weight average molecular weight in therange from about 500 to about 10,000, and has an isocyanatefunctionality of about 2 or greater.

Suitable polyurethane prepolymers are commercially available, forexample, from The Dow Chemical Co., Midland, Mich., under the trademarkHYPOL®, and from Cytec Industries Inc. under the trademark CONATHANE®,and from Air Products and Chemicals, Inc., Allentown, Pa. under thetrademarks AIRTHANE® and VERSATHANE®.

In one embodiment, the content of the polyurethane prepolymer in thecomposition is in the range from about 15 wt % to about 95 wt %, and inanother embodiment, the content of the polyurethane prepolymer in thecomposition is in the range from about 25 wt % to about 90 wt %, and inanother embodiment, the content of the polyurethane prepolymer in thecomposition is in the range from about 35 wt % to about 70 wt %, and inanother embodiment, the content of the polyurethane prepolymer in thecomposition is in the range from about 40 wt % to about 60 wt %. Theforegoing weight percentages are based on the total weight of thecomposition, prior to the crosslinking, foaming and drying steps.

Water

The water used in forming the foam composition of the present inventionshould be deionized or distilled water, although tap water may besuitable in some instances. In one embodiment, the content of the waterin the composition is in the range from about 10 wt % to about 80 wt %,and in another embodiment, the content of the water in the compositionis in the range from about 20 wt % to about 60 wt %, and in anotherembodiment, the content of the water in the composition is in the rangefrom about 30 wt % to about 50 wt %. The foregoing weight percentagesare based on the total weight of the composition, prior to thecrosslinking, foaming and drying steps.

Crosslinking Cyclodextrin with Polyurethane Prepolymers

In one embodiment, the present invention relates to a foam compositionincluding a cyclodextrin crosslinked with a polyurethane prepolymer andhaving a foam structure. The cyclodextrin may be a modifiedcyclodextrin, an unmodified cyclodextrin or a mixture thereof. Thecyclodextrin may be or may be derived from an α-cyclodextrin, aβ-cyclodextrin, a γ-cyclodextrin or a mixture of any two or morethereof. The modified cyclodextrin may be a cyclodextrin modified bybeing bonded to a moiety comprising at least one isocyanate-reactivegroup. The at least one isocyanate-reactive group may include ahydroxyalkyl group, an aminoalkyl group, a carboxyl group, a sulfhydrylgroup, an epoxy group, or a combination of any two or more thereof.

In one embodiment, the foam composition includes a cyclodextrincrosslinked with polyurethane prepolymer and water which comprises areaction product of a reactive isocyanate moiety reacted with at leastone isocyanate-reactive group on the cyclodextrin. In one embodiment,when the cyclodextrin is crosslinked by a polyurethane prepolymer, areactive isocyanate moiety on the polyurethane prepolymer reacts with atleast one isocyanate-reactive group on the cyclodextrin.

In one embodiment, at least two isocyanate-reactive groups on thecyclodextrin react with reactive isocyanate moieties. At least oneisocyanate-reactive group may be a primary hydroxyl group of thecyclodextrin, a secondary hydroxyl group of the cyclodextrin, an activehydrogen or another reactive group on a modifying group attached to thecyclodextrin, or a combination of any two or more thereof. In oneembodiment, at least a portion of the isocyanate-reactive group is theactive hydrogen on a modifying group attached to the cyclodextrin. Ingeneral, the cyclodextrin may be modified in order to improve theavailability of the isocyanate-reactive group for reaction with areactive isocyanate moiety on the polyurethane prepolymer.

As will be recognized, as a result of the crosslinking reaction, it ispossible that some of the cyclodextrin may not be crosslinked. That is,some portion of the cyclodextrin may be completely unreacted or may besingly reacted with the polyurethane prepolymer.

In one embodiment, the foam composition further includes unmodified ornatural cyclodextrin as a component of the cyclodextrin in the reaction.In one embodiment, the foam composition may further includenon-crosslinked modified and/or non-crosslinked unmodified cyclodextrin.In one embodiment, the non-crosslinked modified cyclodextrin may includefree modified and/or unmodified cyclodextrin, modified and/or unmodifiedcyclodextrin singly bonded to the polyurethane prepolymer or a mixtureof any two or more thereof. Thus, modified cyclodextrin and/orunmodified cyclodextrin may be added to the foam after the crosslinking,or may remain unreacted after the crosslinking. In one embodiment, theamount of unreacted modified cyclodextrin is determined by the ratio ofthe quantity of polyurethane prepolymer, and the quantity of water,e.g., the reactive polyisocyanate, to the quantity of active-hydrogen orisocyanate-reactive moieties present in the crosslinking reactionmixture. Additional details on further ingredients alternatively presentin the crosslinking reaction mixture are provided below.

In one embodiment, the foam composition includes unmodified cyclodextrincrosslinked with the polyurethane prepolymer and water. In oneembodiment, unmodified cyclodextrin may be added to the crosslinkingreaction mixture, together with the modified cyclodextrin in thereaction mixture.

In the reaction, the hydroxyl groups of the cyclodextrin (both naturaland modified) and the water will compete to react with the availableisocyanate. As a result, at least a portion of the cyclodextrin becomescrosslinked with the polyurethane prepolymer and some foaming resultsfrom the reaction of the water with some of the isocyanate groups. Asnoted, some of the cyclodextrin may be singly bonded or may be notbonded at all to the polyurethane prepolymer, in which case thecyclodextrin is not crosslinked, but is nevertheless part of the foamcomposition in accordance with the present invention.

Although not to be bound by theory, it appears that the hydroxyl groupson the “body” of cyclodextrin itself have a reactivity towards theisocyanate groups of the polyurethane prepolymer that is similar to thereactivity of water towards the isocyanate groups. It further appearsthat the hydroxyl groups on cyclodextrin modifying substituents, such asin 2- or 3-hydroxypropyl-cyclodextrin, are more reactive toward theisocyanate groups of the polyurethane prepolymer. Thus, it appears thatmodified cyclodextrin is more readily reacted with the isocyanate groupsand therefore is more readily incorporated into the nascent foamcomposition than is natural or unmodified cyclodextrin. These facts canbe taken into consideration when designing a particular foam compositionin accordance with the present invention. Thus, for example, if a higherloading of crosslinked cyclodextrin is desired, either less waterrelative to the amount of cyclodextrin and polyurethane prepolymer) canbe used, more modified cyclodextrin can be used, or a combination ofthese.

In one embodiment, the foam composition of the present invention iscapable of swelling upon absorption of water by increasing its volume byat least 20% greater than original. In another embodiment, the foamcomposition of the present invention is capable of swelling uponabsorption of water by increasing its volume by at least about 100%greater than original. In another embodiment, the foam composition ofthe present invention is capable of swelling upon absorption of water byincreasing its volume by at least about 200% greater than original. Inanother embodiment, the foam composition of the present invention iscapable of swelling upon absorption of water by increasing its volume toabout 300% greater than original. For example, in one embodiment, a foamhaving an initial size, defined as zero percent swelling, upon exposureto moisture for a period of 18 hours, exhibits a volume of 195% of itsoriginal volume, i.e., a swelling to about twice its original volume.

Similarly, in one embodiment, the foam composition of the presentinvention is capable of increasing its own weight upon absorption ofwater, that is, by increasing its initial weight to at least about 20%greater than its original weight. In another embodiment, the foamcomposition of the present invention is capable of increasing its ownweight upon absorption of water by increasing its initial weight toabout 100% greater than its original weight. In another embodiment, thefoam composition of the present invention is capable of increasing itsown weight upon absorption of water by increasing its initial weight toabout 200% greater than its original weight. In another embodiment, thefoam composition of the present invention is capable of increasing itsown weight upon absorption of water by increasing its initial weight toabout 300% greater than its original weight. For example, in oneembodiment, a foam having an initial weight of about 2.0 grams, uponexposure to moisture for a period of 18 hours, exhibits a weightincrease to about 6.5 grams, i.e., a weight increase of about 350%greater than it original weight. In other embodiments, the weightincrease may be in the range from about 300% to about 1800%, and inanother embodiment, up to about 1600% to about 1700%. This waterabsorption/weight increase capability is not expected and quitesurprising, since known foams, while capable of some water absorptionand weight increase, are not believed to be capable of a weight increaseto such a degree.

Additional Components

In one embodiment, in preparing the foam composition, the ingredientscombined for the crosslinking further include an alkylene glycol, apolyalkylene glycol, glycerol or a combination of any two or morethereof. In one embodiment, the addition of these materials provides anelongating, plasticizing effect and greater flexibility to the foam.Thus, in one embodiment, a portion of the alkylene glycol, thepolyalkylene glycol, the glycerol or a combination of any two or morethereof is chemically bonded to the polyurethane prepolymer. Thealkylene glycol, polyalkylene glycol, glycerol or combination of any twoor more thereof may be present in the composition up to about 20 wt % ofthe composition. The foregoing weight percentages are based on the totalweight of the composition, prior to the crosslinking, foaming and dryingsteps.

As will be understood, addition of such hydroxyl-containing additivescan result in the addition of these into the foam structure, by any oneor more of crosslinking, single bonding or simply being incorporatedphysically into the foam structure, since the hydroxyl groups will bereactive similar to the hydroxyl groups in the cyclodextrin and thewater. These same glycols can be used to form the partially polymerizedpolyurethane prepolymer.

In one embodiment, at least a portion of the modified cyclodextrin iscomplexed with a suitably selected molecule. As is well known in theart, cyclodextrins are capable of complexing a wide variety of organicmolecules, including pharmaceuticals, perfumes, fragrances, etc., e.g.,by partially or completely holding molecules of the complexed materialwithin the cyclodextrin cavity. Thus, the foam composition of thepresent invention may be used in delivery of any suitable such material.The content of the cyclodextrin-complexed material in the foamcomposition depends upon the cyclodextrin content. In one embodiment,the content of the cyclodextrin-complexed material in the foamcomposition may range from about 0.01 wt % to about 30 wt %, and inanother embodiment, the content of the cyclodextrin-complexed materialin the foam composition may range from about 0.1 wt % to about 10 wt %,and in yet another embodiment, the content of the cyclodextrin-complexedmaterial in the foam composition may range from about 0.5 wt % to about5 wt %.

In one embodiment, the foregoing foam may be used in an article such asa personal care product. Exemplary personal care products include,without limitation, one or more of a bandage, a wound dressing, a wipe,a diaper, a diaper pant, a training pant, an absorbent underpant, aprotective swimming undergarment, an incontinence garment, a pantyshield or liner, a feminine hygiene product or a perspiration shield.Other suitable articles and personal care products also may include thefoam composition of the present invention.

Process for Preparing the Foam

In one embodiment, the present invention relates to a process forpreparing a foam, in which the process includes:

providing a cyclodextrin;

providing a polyurethane prepolymer;

providing water;

combining the cyclodextrin, the water and the polyurethane prepolymer;and

reacting the polyurethane prepolymer with the water and the cyclodextrinto form a foam composition comprising the cyclodextrin crosslinked withthe polyurethane prepolymer and having a foam structure. In oneembodiment, as noted above, quantities of the modified cyclodextrin, thewater and the polyurethane prepolymer are selected to result information of the foam. That is, the ratio of the ingredients is selectedto produce a desired foam that is stable, swellable and exhibits thedesired properties as described further herein. In addition, thequantity of water is controlled to avoid the formation of a hydrogel asopposed to the foam.

The reaction may be carried out at a temperature from about 20° C. toabout 120° C., in one embodiment, from about 35° C. to about 90° C., andin one embodiment, at about 50° C., for a suitable period of time. Asuitable period of time may range from about 1 minute to about 18 hours,in one embodiment, from about 10 minutes to about 8 hours, and inanother embodiment, from about 15 minutes to about 2 hours. As will berecognized, the greater the temperature, the faster the reaction, andlikely, the greater the volume of the foam produced. The temperature maybe adjusted in accordance with the type of substrate on which the foamis formed, in such embodiment.

In one exemplary embodiment, the ingredients are mixed at roomtemperature, allowed to react, in which both the crosslinking reactionof polyurethane prepolymer isocyanate with cyclodextrin hydroxyl groupsand optionally with other active hydrogen-containing moieties and thefoam forming reaction of polyurethane prepolymer isocyanate with watertake place, for about 5 minutes, and then resulting foam composition isplaced in an oven at a temperature of about 50° C. to dry for a periodof about 2 hours. In another embodiment, the ingredients are mixed atroom temperature, allowed to react for about 15 minutes, and the foamcomposition is then placed in an oven at a temperature of about 100° C.to dry for a period of about 1 hour.

In one embodiment, the modified cyclodextrin used in this method may beany of the cyclodextrins disclosed above. In one embodiment, thecyclodextrin is a modified cyclodextrin and in another embodiment thecyclodextrin is an unmodified cyclodextrin and in yet anotherembodiment, the cyclodextrin is a mixture of any two or morecyclodextrins. That is, the mixture may be of any two or more unmodifiedcyclodextrins, any two or more modified cyclodextrins, or any two ormore unmodified and modified cyclodextrins. The polyurethane prepolymerused in this method may be any of the polyurethane prepolymers disclosedabove.

In one embodiment, the step of combining the modified cyclodextrin withthe polyurethane prepolymer may be carried out at room temperature. Inanother embodiment, the step of combining may be carried out at anelevated temperature, in order to accelerate the reaction and to enhancethe foam formation. As will be recognized, when the crosslinkingreaction between the cyclodextrin, water and polyurethane prepolymer iscarried out at an elevated temperature, carbon dioxide released duringthe reaction will cause formation of the foam and thereby the foamcomposition will be formed. In one embodiment, the water included in thereaction mixture is adjusted to provide a controlled foam formation. Thewater reacts with the isocyanate group of the polyurethane prepolymer,forming an unstable carbamic acid which reacts with a further isocyanategroup and releases carbon dioxide.

In one embodiment, other foaming agents known in the polyurethane artsmay be used for increasing the volume of the foam composition. Thus,foaming agents such as fluorocarbons or low molecular weighthydrocarbons may be added to adjust the amount of foaming.

In carrying out the combination and allowing the polyurethane prepolymerto react with and crosslink the modified cyclodextrin to form the foam,the reactive isocyanate groups preferentially react with the more easilyaccessible isocyanate-reactive moieties. Thus, for example, as notedabove, the hydroxyl group on the hydroxypropyl group of a cyclodextrinmodified by 2- or 3-hydroxypropyl should be more accessible and therebymore reactive than would be the hydroxyl groups on the cyclodextrinmolecule itself. Similarly, it would be expected that the primaryhydroxyl group on the 6-position of the cyclodextrin molecule would bemore reactive to a reactive isocyanate group than would be the secondaryhydroxyl groups at the 2- and/or 3-position of the cyclodextrinmolecule.

It will be recognized by those in the art that a very large number ofpossible isomers of modified cyclodextrins are possible, and that a verylarge number of possible isomers for the crosslinked modified orunmodified cyclodextrin are possible. Since there are 6, 7 or 8glucopyranose rings in the usual α-, β-, and γ-cyclodextrin molecules(respectively) and each glucopyranose ring includes three hydroxylgroups, any one or more of which may be modified and/or reacted with thereactive isocyanate group, a huge number of isomers are possible. Aswill be recognized, if more than one modifying group is used on thecyclodextrin, the numbers go much higher.

In one embodiment, the crosslinking reaction between the modifiedcyclodextrin and the water and the polyurethane prepolymer may becarried out as follows. The modified cyclodextrin is dissolved in waterat a concentration ranging from 0.1 wt % to saturation, depending on theobjective. The solution of modified cyclodextrin is mixed with apolyurethane prepolymer at a temperature ranging from about 10° C. toabout 120° C., as described herein. The mixed solution is coated onto asubstrate such as a release liner or a polymeric backing and iscrosslinked. The ratio of modified cyclodextrin to water to polyurethaneprepolymer is selected to obtain the desired foam.

In another embodiment, either the solution of modified cyclodextrin(with or without additional ingredients in the solution) or thepolyurethane prepolymer may be applied to the substrate first, followedby the other of the modified cyclodextrin or polyurethane prepolymer,and thereafter the two components are allowed to react to form thecross-linked foam composition. In this embodiment, the individualcomponents may be applied independently by any suitable means, includingspraying, roll coating, knife coating, doctor blade coating, etc. In onesuch embodiment, both components are applied by spraying onto thesubstrate.

In one embodiment, the ratio of modified cyclodextrin to polyurethaneprepolymer may range from about 1:10 to about 10:1. In one embodiment,the ratio of modified cyclodextrin to polyurethane prepolymer may rangefrom about 1:5 to about 5:1. In one embodiment, the ratio of modifiedcyclodextrin to polyurethane prepolymer may range from about 1:3 toabout 3:1. In one embodiment, the ratio of modified cyclodextrin topolyurethane prepolymer is about 1:2. That is, when the ratio ofmodified cyclodextrin to polyurethane prepolymer is about 1:2, onaverage, each molecule of modified cyclodextrin can potentially reactwith two molecules of polyurethane prepolymer in the crosslinkingreaction. In one such embodiment, the two molecules of polyurethaneprepolymer in the crosslinking reaction are two different molecules ofpolyurethane prepolymer. Of course, with cyclodextrins containing fromsix to eight glucopyranose rings, each having as many as three hydroxylgroups available for reaction, any one molecule of modified cyclodextrinmay be cross-linked to many more than two polyurethane prepolymermolecules. In addition, in an embodiment in which the modifying group ofthe modified cyclodextrin includes a plurality of hydroxyl or otherisocyanate-reactive groups, the potential number of crosslinking sitesbecomes even greater.

In one embodiment, the process of the present invention further includesproviding a polyol, e.g., an alkylene glycol, a polyalkylene glycol,glycerol or a combination of any two or more thereof and combining thealkylene glycol, the polyalkylene glycol, the glycerol or thecombination of any two or more thereof with the modified cyclodextrinand the polyurethane prepolymer in the combining step or, in analternative embodiment, premixing the alkylene glycol, the polyalkyleneglycol, the glycerol or the combination of any two or more thereof withthe modified cyclodextrin prior to the combining step. That is, in oneembodiment, the foregoing materials may be added to the reaction mixtureand will become part of the foam composition, including in at least someembodiments, in which the alkylene glycol, polyalkylene glycol and/orglycerin is crosslinked with or bonded to other components of the foam,including the modified cyclodextrin and any free cyclodextrin which mayalso be present, by the polyurethane prepolymer. In one embodiment,addition of the alkylene glycol, the polyalkylene glycol, the glycerolor the combination of any two or more thereof with the modifiedcyclodextrin results in the formation of a foam having improvedflexibility, when the mixture is cross-linked by the polyurethaneprepolymer. In such embodiments, the relative quantities of theingredients can be adjusted to control the features of the producedfoam. For example, if a more rigid foam is desired, then less or none ofthe additional polyol would be added, and/or a polyurethane prepolymerhaving less flexibility or smaller size (i.e., molecular weight) wouldbe used. If a less rigid foam is desired, then more of the additionalpolyol and/or a more flexible or higher molecular weight polyurethaneprepolymer would be used. If a foam having larger cells is desired, thena higher temperature may be employed or, alternatively, an externalfoaming agent may be added to the reaction mixture. The amount of wateradded to the reaction mixture may also have an effect on the quality ofthe foam, and in one embodiment, is selected to avoid formation of ahydrogel.

In one embodiment, the polyol includes polyalkylene polyols or polyolscomprising ethylene-oxide-derived monomeric units. In one embodiment,the polyol is water soluble. in one embodiment, the polyol has a weightaverage molecular weight in the range from about 200 to about 30,000. Asnoted above, in one embodiment, the weight average molecular weight ofthe polyurethane prepolymer may range from about 500 to about 30,000 orhigher, and in another, from about 500 to about 10,000.

In one embodiment, the process of the present invention further includescombining an unmodified cyclodextrin with the modified cyclodextrin andthe polyurethane prepolymer in the combining or premixing the unmodifiedcyclodextrin with the modified cyclodextrin prior to the step ofcombining. Thus, in this embodiment, the foam will further includeunmodified cyclodextrin as part of the foam. In one embodiment, theunmodified cyclodextrin is crosslinked with the polyurethane prepolymer.

In one embodiment, the foam further comprises non-crosslinked modifiedand/or non-crosslinked unmodified cyclodextrin. In this embodiment, someof the cyclodextrin, whether modified or unmodified, is either presentas free cyclodextrin (modified or not modified) or present as modifiedor unmodified cyclodextrin which is singly-bonded to the polyurethaneprepolymer. Thus, the modified or unmodified cyclodextrin that is singlybonded is chemically attached to the foam, while any modified orunmodified cyclodextrin that is not bonded may form a part of the foam,but is not chemically bonded and is thus subject to dissolution in waterabsorbed by the foam.

Thus, in one embodiment, the foam further comprises non-crosslinkedmodified cyclodextrin, free modified and/or unmodified cyclodextrin,modified and/or unmodified cyclodextrin singly bonded to thepolyurethane prepolymer or a mixture of any two or more thereof.

In one embodiment, at least a portion of the cyclodextrin is complexed.The cyclodextrin may be provided in a complexed form, or a compound ormaterial to be complexed may be added to the crosslinking reactionmixture (if it is not subject to reaction with the polyurethaneprepolymer) or may be added to the foam formed by the crosslinkingreaction subsequent to completion of the crosslinking reaction.

EXAMPLES

Selected embodiments of the foam composition in accordance with thepresent invention are presented. These examples are provided toillustrate the invention and are not intended to limit the scope of theinvention which is limited only by the scope of the claims appendedhereto.

Preparation of Solution A

Into 504 g of demineralized water, a 64 g (12.70 wt %) sample ofα-cyclodextrin is dissolved. This is Solution A as used in the followingExamples 1-11 shown in Table 1.

Preparation of Solution B

Into 151.55 g of demineralized water, a 16.58 g (10.94 wt %) sample ofhydroxypropyl-β-cyclodextrin is dissolved. This is Solution B as used inthe following Examples 1-11 shown in Table 1.

Polyurethane Prepolymer

In the following Examples 1-11, the polyurethane prepolymer used isHYPOL® 2002, which is a TDI-based partially polymerized polyurethaneprepolymer, from DOW Chemical Co.

Examples 1-11

In the following Examples 1-11, the above prepared Solution A orSolution B or none and the polyurethane prepolymer are used in theindicated amounts. The prepolymer is weighed into a beaker, and theindicated amounts of water or cyclodextrin is added. The resultingmixture is stirred at 23° C. until a homogeneous white color appears.The resulting mixture is then poured onto plates and placed in an ovenat 50° C. to accelerate the reaction. A range of water amounts isevaluated to determine foam properties. All measurements are made atroom temperature.

As shown in Table 1, foam compositions in accordance with variousembodiments of the present invention provide quite high swellability,high weight gain ability, and high odor-absorbing activity, whilemaintaining the foam structure. In all of the Examples 1-11, an opencell foam is formed.

In the examples shown in Table 1, the fluid capacities are measured asfollows. For the initial fluid capacity, the dry foam sample is weighed(“Initial wt.” in Table 1) and is then immersed in water for 30 minutes,taken out and weighed (“30 min. wt.”), and the percent weight increase(“30 min. %”) is determined by the formula (wet weight−dry weight)/dryweight.

The same procedure is used for the 18 hour samples, except that the foamsamples are soaked in water for 18 hours, then weighed (“18 hr. saturatewt.”). The same samples are then drained by draining for 30 seconds thewater that is not absorbed into the foam or bound to the foam, and thesamples are then weighed again (“18 hr. drain wt.”). The samecalculation as above is performed to determine the percent weightincrease (“18 hr. saturate %” and “18 hr. drain %”, respectively).

The odor absorption test is carried out as follows. A 1 g. sample of thefoam is maintained in the presence of 2 ml of a solution containing 1200ppm of the valeric or butyric acid, for 8 hours at a temperature of 31°C. The resultant foam sample is graded against the odor of a foam samplethat has not been exposed to the respective acids, on the followingscale:

Grade 1 same smell as the control;

Grade 2 a slight odor of the acid;

Grade 3 a strong odor, but less strong that the 1200 ppm standard;

Grade 4 an odor of the same strength as the 1200 ppm standard.

As shown by the results in the Table 1, the cyclodextrin containing foamcompositions, in accordance with the present invention, show a muchhigher absorption of the acid odors.

TABLE 1 Water Absorption Water Absorption PUP¹ CD Water Absorption 18hr. 18 hr. 18 hr. 18 hr. Odor absorption Ex. Hypol ® Water/CD² Initial30 min. 30 min. saturate saturate drain drain Valeric Butyric No. (g.)(g.) wt. wt. % wt. % wt. % acid acid 1 29.17 3.2 water 1.2 4.25 254 9.62702 8.63 619 4 3 2 36.5 36.5 water 0.83 8.05 870 8.17 884 7.13 759 4 3 330.89 102.96 1.03 6.34 516 6.51 532 5.57 441 4 3 water 9 41.1 4.56 A0.92 16.33 1675 17.62 1815 16.4 1683 2 2 7 27.62 27.62 A 1.18 10.06 7539.87 719 7.89 569 2 1 8 37.0 123.0 A 1.81 7.03 288 7.39 308 6.9 281 1 110 35.29 3.92 B 1.37 15.08 1001 19.37 1314 15.79 1053 2 2 29.99 7.5 B 1132.48 32.48 B 1.17 10.57 803 11.04 844 8.51 627 1 2 27.1 90 B ¹PUP isthe polyurethane prepolymer, HYPOL ®2002; CD is the Solution A orSolution B. ²Water is used for control samples; Solution A or Solution Bare added as indicated by “A” and “B”.

Personal Care Products

In one embodiment, the present invention further relates to a processfor preparing a foam-containing personal care product, comprising:

providing a cyclodextrin;

providing a polyurethane prepolymer;

providing water; and

combining the cyclodextrin, the water and the polyurethane prepolymer;and

reacting the polyurethane prepolymer with the water and the cyclodextrinto form a foam composition comprising the cyclodextrin crosslinked withthe polyurethane prepolymer and having a foam structure; and

applying the cyclodextrin, the water and the polyurethane prepolymer toa substrate.

In one embodiment, the step of combining is followed by the step ofreacting the polyurethane prepolymer with the water and crosslinking thecyclodextrin, which is in turn followed by applying the reactedcyclodextrin and polyurethane prepolymer to the substrate. In oneembodiment, the step of combining is followed by the step of applyingthe combined cyclodextrin, water and polyurethane prepolymer to thesubstrate, which is followed by reacting the polyurethane prepolymerwith the water and crosslinking the cyclodextrin. Thus, the crosslinkingreaction in the allowing step may take place before, during or after theapplying step. In one embodiment, the crosslinking reaction in thereacting step begins as soon as the cyclodextrin and water andpolyurethane prepolymer are combined and continues during and subsequentto the step of applying the combined cyclodextrin and polyurethaneprepolymer to the substrate.

In one embodiment, the substrate comprises a backing layer or a releaseliner on at least a portion of which the foam forms a layer. The backinglayer and the release liner may be formed of any suitable material,depending primarily upon what type of personal care product is to beformed.

In one embodiment of the personal care foam product, the foam is in theform of a patch, in which the foam is either adhered or not adhered to abacking layer. The foam composition may also have a release liner on theside thereof away from the backing layer, particularly when the foamcomposition is adhesive in nature. The backing layer may furthercomprise a pressure sensitive adhesive layer to enhance adhesion to theuser's anatomy or to other parts of the personal care product.

The term “backing layer” refers to that component of an article such asa personal care product, for example, an infant diaper, sanitary napkin,adult incontinence garment or the like which is worn during normal usefurthest from the user's body and which may serve to minimize or preventthe exudation leakage of the absorbed liquid, or to protect theunderlying elements of the user's skin.

The backing layer can be any material convenient to the particularapplication. The backing layer can be made of any suitable natural orsynthetic fiber or fabric, and can be woven or non-woven. Variousmaterials can be used as the backing material. Specific examples includepapers, non-woven fabrics, natural fiber (e.g., cotton) fabrics,synthetic resin fabrics, synthetic resin films, synthetic resin foams,mesh-form or network papers, woven fabrics, and knit fabrics. Surgicaltapes, medical pressure-sensitive adhesive sheets, pressure-sensitiveadhesive dressings, constructed with the above films, foams, non-wovenfabrics, woven fabrics, or knits can also be used as a backing material.The backing layer can also be in the form of an impermeable or permeablefoam made from natural materials or from synthetic materials such aspolyolefin, polyester, polyurethane, and the like.

Examples of suitable backing materials include polyurethanes such asESTANE® polyurethanes (B.F. Goodrich, Cleveland, Ohio) including, forexample, ESTANE® 58237, ESTANE® 58245, and ESTANE® 58309. Other suitablebacking materials include elastomeric polyester such as HYTREL®polyester elastomer (E.I. du Pont de Nemours & Co., Wilmington, Del.),blends of polyurethane and polyester, and polyvinyl chloride.Thermoplastic polyether-amide block copolymers such as PEBAX® 2533 andPEBAX® 3533 (available from Atochem Co.); and polyether-ester blockcopolymers may also be used.

In one embodiment, the backing layer has a thickness of from about 15 toabout 100 micrometers or more, in one embodiment from about 20 to about80 micrometers and in another embodiment, from about 20 to about 50micrometers.

In one embodiment, the backing layer is a transparent, conformable,moisture vapor permeable film. In one embodiment, the backing layer isalso elastomeric. In one embodiment, the backing film is impermeable toliquid water and has a moisture vapor transmission rate (MVTR) of atleast 300 g per 24 hr at 37° C. and 80% relative humidity.

In an embodiment in which the backing extends beyond the area of thefoam composition, the backing may include an adhesive that may alsoserve as a skin contact adhesive around the border of the backing layer.

In one embodiment, the personal care product may include a liquidpermeable skin or wound contacting layer and an outer, liquid-imperviousbacking layer, in which the foam is between these two layers.

In one embodiment, the backing layer may extend beyond at least one edgeof the foam to provide an adhesive coated margin adjacent to the foamfor adhering the product to a surface, such as to the skin of a patientadjacent to the wound being treated. In one embodiment, an adhesivecoated margin may extend around all sides of the product. In anotherembodiment, there is no adhesive-coated margin. In another embodiment,the foam is non-adherent to prevent the product from sticking to asurface or the skin of a patient adjacent to the wound being treated.

The release liner can be any suitable material known to the art or tothe literature and generally is a plastic which, in one embodiment, therelease liner can be a plastic such as a polyolefin, for examplepolyethylene or polypropylene, or it can be polyvinylchloride, nylon,and the like. In one embodiment, it can contain a release liner thereonsuch as a thin layer of silicone. In such an embodiment, the product canbe applied to a substrate such as human skin simply by removing therelease liner and applying thereto the odor-absorbing foam containingthe backing.

In one embodiment, the personal care product comprises one or more of abandage, a wound dressing, a wipe, a diaper, a diaper pant, a trainingpant, an absorbent underpant, a protective swimming undergarment, anincontinence garment, a panty shield or liner, a feminine hygieneproduct or a perspiration shield. Other personal care products known inthe art may also be included within the scope of the present invention.In one embodiment, the personal care product may be any such productthat can benefit from the presence of a odor-absorbing foam somewhere inits structure.

In one embodiment, the odor-absorbing foam used in the personal careproduct further includes a quantity of unmodified cyclodextrincrosslinked with the polyurethane prepolymer and water or simply as acomponent of the odor-absorbing foam without being crosslinked. Theunmodified cyclodextrin may be unbonded or may be singly bonded to theodor-absorbing foam structure.

In one embodiment, at least a portion of the unmodified cyclodextrin iscomplexed. That is, in one embodiment, at least a portion of theunmodified cyclodextrin includes another material, such as apharmaceutical, a perfume or some other material in or partially thecavity of the cyclodextrin molecule.

In one embodiment, at least a portion of the modified cyclodextrin iscomplexed. That is, in one embodiment, at least a portion of themodified cyclodextrin includes another material, such as apharmaceutical, a perfume or some other material in or partially thecavity of the cyclodextrin molecule.

In one embodiment, the personal care product may be made by any of thevarious process alternatives described herein.

In one embodiment, the present invention relates to a personal careproduct including an odor-absorbing foam, including a modifiedcyclodextrin crosslinked with a polyurethane prepolymer, in which theodor-absorbing foam is applied to a substrate, wherein a ratio of themodified cyclodextrin to the water and the polyurethane prepolymer isselected to result in formation of the odor-absorbing foam.

While the invention has been explained in relation to various of itsembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover modifications as fall within thescope of the claims.

What is claimed is:
 1. A process comprising: providing a cyclodextrin with at least one isocyanate-reactive group on at least a portion of the cyclodextrin; wherein the content of the cyclodextrin in the composition is from 0.5 wt % to 50 wt %; providing a polyurethane prepolymer; providing water; wherein the content of the water in the composition is in the range from 10 wt. % to 80 wt.; combining the cyclodextrin, the water and the polyurethane prepolymer; and reacting the polyurethane prepolymer with the water and the cyclodextrin to form a foam composition comprising the cyclodextrin crosslinked with the polyurethane prepolymer and having a foam structure, wherein the cyclodextrin crosslinked with a polyurethane prepolymer comprises a reaction product of a reactive isocyanate moiety reacted with at least one isocyanate-reactive group on at least a portion of the cyclodextrin, and the isocyanate-reactive group is an active hydrogen on a modifying group attached to the at least a portion of the cyclodextrin. 2: The process of claim 1 wherein the cyclodextrin is an α-cyclodextrin, a β-cyclodextrin, a γ-cyclodextrin or a mixture of any two or more thereof. 3: The process of claim 1 wherein the at least one isocyanate-reactive group comprises a hydroxyalkyl group, an aminoalkyl group, a carboxyl group, a sulfhydryl group, an epoxy group, or a combination of any two or more thereof. 4: The process of claim 1 wherein the reactive isocyanate moiety comprises an aliphatic, cycloaliphatic, arylaliphatic, heterocyclic or aromatic polyisocyanate or a mixture thereof. 5: The process of claim 1 wherein the polyurethane prepolymer has an average isocyanate functionality of about 2 or greater. 6: The process of claim 1 wherein a ratio of the water to the cyclodextrin and the polyurethane prepolymer is selected to result in formation of the foam. 7: The process of claim 6 wherein the ratio is controlled to avoid formation of a hydrogel. 8: The process of claim 1 wherein the at least one isocyanate-reactive group is a primary hydroxyl group of the cyclodextrin, a secondary hydroxyl group of the cyclodextrin, an active hydrogen on a modifying group attached to the cyclodextrin, or a combination of any two or more thereof. 9: The process of claim 1 further comprising providing an alkylene glycol, a polyalkylene glycol, glycerol or a combination of any two or more thereof and combining the alkylene glycol, the polyalkylene glycol, the glycerol or the combination of any two or more thereof with one or more of the cyclodextrin, the water and the polyurethane prepolymer prior to or during the reacting. 10: The process of claim 1 wherein a portion of the cyclodextrin is not cross-linked. 11: The process of claim 10 wherein the non-crosslinked cyclodextrin comprises free modified and/or unmodified cyclodextrin, modified and/or unmodified cyclodextrin singly bonded to the polyurethane prepolymer or a mixture of any two or more thereof. 12: The process of claim 1 wherein the reacting is carried out at a temperature in the range from about 30° C. to about 120° C. 13: The process of claim 1 wherein at least a portion of the modified cyclodextrin is complexed. 14: The process of claim 1 wherein the foam has an original volume and upon absorption of water is capable of swelling to a volume at least about 20% greater than its original volume. 15: The process of claim 1 wherein the foam has an original weight and upon absorption of water is capable of increasing its weight to a weight at least about 20% greater than its original weight. 16: The process of claim 1 wherein the combining further comprises applying the cyclodextrin, the polyurethane prepolymer and the water, in any order, to a substrate. 17: A personal care product including a foam composition made by the process of claim
 1. 18: A process for preparing a foam-containing personal care product, comprising: providing a cyclodextrin with at least one isocyanate-reactive group on at least a portion of the cyclodextrin; wherein the content of the cyclodextrin in the composition is from 0.5 wt % to 50 wt %; providing a polyurethane prepolymer; providing water; wherein the content of the water in the composition is in the range from 10 wt. % to 80 wt.; combining the cyclodextrin, the water and the polyurethane prepolymer; reacting the polyurethane prepolymer with the water and the cyclodextrin to form a foam composition comprising the cyclodextrin crosslinked with the polyurethane prepolymer and having a foam structure; and applying the cyclodextrin, the water and the polyurethane prepolymer to a substrate, wherein the cyclodextrin crosslinked with a polyurethane prepolymer comprises a reaction product of a reactive isocyanate moiety reacted with at least one isocyanate-reactive group on at least a portion of the cyclodextrin, and the isocyanate-reactive group is an active hydrogen on a modifying group attached to the at least a portion of the cyclodextrin. 19: The process of claim 18 wherein the substrate comprises an element of the personal care product. 20: The process of claim 19 wherein the element comprises a backing layer on at least a portion of which the foam forms a layer. 21: The process of claim 18 wherein the personal care product comprises one or more of a bandage, a wound dressing, a wipe, a diaper, a diaper pant, a training pant, an absorbent underpant, a protective swimming undergarment, an incontinence garment, a panty shield or liner, a feminine hygiene product or a perspiration shield. 22: The process of claim 18 wherein the applying the combined cyclodextrin and polyurethane prepolymer to a substrate is carried out prior to or during the reacting. 23: The process of claim 18 wherein the applying the combined cyclodextrin and polyurethane prepolymer to a substrate is carried out subsequent to the reacting. 